The use of a catalyst on an industrial scale requires that it meets some basic requirements for good operational stability of the polymerization process.
It is already known from the literature that catalysts of polyolefins, having a mechanism of coordination polymerization, faithfully reproduce the original morphology of the catalyst (replication effect).
However, it was observed during the process of development of monofilament fibber based on a particular polyethylene resin, said monofilament possessing special characteristics of high performance and which can be processed in conventional extrusion equipment, that the catalyst displayed considerable difficulties in the implementation of stages that involve large-scale preparation of the polymer. These difficulties mainly occur in relation to the mixed catalyst obtained by grinding, which leads to an irregular morphology.
However, this irregular morphology combined with the high activity of the catalyst leads to an uncontrolled polymerization reaction, when conditions of high partial pressure are used, which in turn is reflected in stages of polymerization and processing of the polymer and leads to problems, mainly owing to formation of agglomerates in the reactor.
The industrial implementation of catalyst based on mixing by grinding, especially for the catalyst of alumina and magnesium, presents a kinetics polymerization of difficult control and, as noted above, the consequence is the formation of agglomerates. This problem makes it difficult to use in continuous processes as its application is only feasible with addition of anti-agglutinant agents. Another way of avoiding these problems is to use smaller charges of monomer. Depending on the “class” of polyethylene desired and on the use of these smaller charges, the commitment of productivity resulting from these measures may make impracticable the industrial implementation of the catalyst. An example of this is the synthesis of a polyethylene fibber “class” where, formation of agglomerates resulting from the extremely high initial activity and the poor morphology resulting from the grinding process, continuous operation of industrial plant becomes impracticable.
Researches continue being developed, searching for a catalyst that displays versatility. A desirable quality in the implementation of an industrial catalyst consists of its capacity for production of different “classes” of products without needing to change the catalytic system, which greatly simplifies operation of the system.